The present invention relates to a liquid ejecting apparatus for refilling liquid from a main tank to a subtank via a liquid supply passage and supplying the liquid from the subtank to a liquid ejecting head, an evacuation tank for evacuating liquid used in the liquid ejecting apparatus and a method of evacuating liquid of the liquid ejecting apparatus.
Heretofore, a liquid ejecting apparatus for ejecting liquid toward a target from a nozzle of a liquid ejecting head, such as an ink-jet printer is known. Some ink-jet printers have configuration of a so-called off-carriage type in which an ink cartridge as main tank for storing ink as liquid is arranged on the side of the main body of the printer. For the ink cartridge, plural ink cartridges are provided every ink of each color such as black, cyan, magenta and yellow. In case the off-carriage type is adopted, the printer may be miniaturized and thinned in case an ink cartridge having large capacity is used for printing on large paper for example and to increase the degree of freedom in a layout of ink cartridges.
In the ink-jet printer of the off-carriage type, to stabilize the supply of ink, a subtank may be provided on an ink passage between an ink cartridge to a recording head as a liquid ejecting head. The subtank is mounted on a carriage, receives ink from the ink cartridge via a tube for refilling ink and supplies the ink to the recording head.
Recently, for an image formed by the ink-jet printer, high image quality is required and accordingly, the type of ink has a tendency to be increased. Such ink is different depending upon material, an additive agent, color and concentration, and is used in consideration of a record medium and a purpose. For example, black ink for forming a high quality of image on glossy paper and black ink for forming an image on plain paper by high-speed printing may be different in a type. To enhance a gray scale, black ink may be used in place of gray ink for example.
The types of ink are increased as described above and in the meantime, the number of ink passage of a subtank and a tube mounted in the ink-jet printer is limited. Therefore, it is required that inks of different types are used in the same ink passage. In such a case, after already used ink is fully evacuated from a passage, ink of a different type is required to be filled. Particularly, in the ink-jet printer of the off-carriage type, as the passage from the ink cartridge to the recording head is long, much ink remains in the ink passage and a process for evacuating ink is important.
For a method of evacuating residual ink in the ink passage, a method of refilling ink in the tube for refilling ink and in the subtank provided above the ink cartridge in a direction of gravity by flowing the ink according to the gravity to flow back it to the ink cartridge is proposed.
However, in the ink cartridge, so-called deaerated ink in which gas dissolved in ink is removed is stored. Therefore, this method has a problem that when ink is flowed back, bubbles remained in the ink passage are mixed with the deaerated ink in the ink cartridge and the quality of ink is deteriorated.
Besides, a method of gathering the flowed back ink to a dedicated waste liquid tank is proposed. However, quantity of ink stored in the waste liquid tank is limited.
Besides, in the method of flowing back ink according to only gravity, a small ink droplet adheres to the inside wall of the tube for refilling ink cannot be evacuated. Besides, the ink passage has a location where it is difficult to evacuate residual ink according to only gravity and has a problem that ink is left.